10 



pollen of its own kind. But the oxlip is a sort of unde- 

 cided tertium quid, an undifferentiated relic of the old 

 undivided ancestral form, which grows in intermediate 

 situations, and crosses now with one plant and now with 

 the other, so preventing either from finally taking its 

 stand as a truly separate species. 



The reason why the thoroughgoing primroses do not 

 cross with the thoroughgoing cowslips is easy enough to 

 understand : they are seldom both in blossom together. 

 This, again, naturally results from the form and habit of 

 the two flowers. In both, the head of bloom is produced 

 from material laid by during the past year in the peren- 

 nial rootstock ; and in both, the buds begin to sprout as 

 soon as the weather grows warm enough for them to 

 venture forth with safety. But the " rathe primrose" 

 bursts into blossom first, because it has only to produce 

 short subsidiary stalks for each separate flower ; the cow- 

 slip lingers somewhat later, because it has to send up a 

 stout common stem, besides forming the minor pedicels 

 for the individual cups. Their other differences are all 

 of similar small kinds. The primrose, standing straight 

 up from the earth, receives the fertilizing bee or butter- 

 fly on the face of its wide-open corolla ; the cowslip, a 

 little pendulous by nature, receives its guest from below, 

 or from one side, and so has its blossom more bell-shaped 

 as well as less widely expanded. The primrose is pale to 

 suit its own special insect visitors ; the cowslip is a deeper 

 yellow, melting almost into orange, to meet the tastes of 

 a somewhat different and perhaps more daintily aesthetic 

 circle. At bottom, however, both flowers are very nearly 

 the same, and their peculiarities are all specially intended 

 to insure a very high type of cross-fertilization. 



Observe that in both flowers the corolla, though deeply 

 divided into five notched lobes or sections, is yet not 



